[marx290]

I'm also rather interested in getting some HC samples tested.

Looking for a high purity propane, I called and asked around Portland, finding mainly blank stares and confused people. I did eventually get a hold of an Airgas special gas salesman. He said he could get a 20lb tank of 99.5 percent pure, for about $220. Seemed kind of pricey, but then again maybe comparable to some halogen refrigerants (I don't buy 'em). I told him I would consider it in the future.

Personally, I'd rather spend that money on trying to clean up HD-5 myself. It appears there are some proven methods for removing the mercaptan and water, which I want to experiment further, but I'd like to try my hand at further separation of the gases. A fractionating column. I woukd think the ethylene and methane, even in small amounts, might cause some problems, since these are not likely to condense anywhere in a normal system. The butane and isobutane are going to contribute to some glide, I guess, and may not be too troublesome, but I'd like to remove them nonetheless; even if just for the challenge. Propylene has such a close boiling point to propane, that it will be hard to fractionate. It's probably the least of my worries though.